[AT] Horsepower Question

[charlie hill]

Yes but you don't always get torque numbers out of manufacturers.   So, you 
have to deal with HP.  As a rule of thumb if you are getting a big HP number 
for a small displacement engine it's probably not a reliable indicator of 
real world usable power.

--------------------------------------------------
From: "Ben Wagner" <supera1948 at gmail.com>
Sent: Wednesday, October 06, 2010 10:17 AM
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Subject: Re: [AT] Horsepower Question

>  On 10/6/2010 10:00 AM, charlie hill wrote:
>> Ben,  the lawn mower engine is rated in gross hp with no drive train 
>> load.
>> The tractor engine is rated at net hp, either at the wheels or the PTO.
>> There may well be some fudging on the lawn mower engine as well.  Also, 
>> HP
>> is torque in ft/lbs.  times RPM.  You can make hp with high rpms and low
>> torque or high torque and low rpm.   Your tractor is high torque and low
>> rpm.  that is what allows it to move a load easily.
>>
>> Charlie
>>
>> --------------------------------------------------
>> From: "Ben Wagner"<supera1948 at gmail.com>
>> Sent: Wednesday, October 06, 2010 9:00 AM
>> To: "At"<at at lists.antique-tractor.com>
>> Subject: [AT] Horsepower Question
>>
>>>   Here is a puzzler that maybe someone with a better knowledge of
>>> engines can answer.   I was asked this question, and had to announce
>>> that I needed to look it up.  What better place than the AT Mailing?
>>>
>>> I have a Super A with four cylinders, producing c. 20 HP.
>>>
>>> I have a lawnmower, with an engine that says it is also 20 HP, with only
>>> two cylinders.
>>>
>>> What is going on?  Is this two different measures of HP?  Or has
>>> technology improved that much?   What makes a little two cylinder "small
>>> engine" have the same HP as four cylinder "tractor" engine.
>>>
>>> Thanks,
>>> Ben Wagner
>>>
>>>
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>>>
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> So in reality, horsepower is not really the important number; torque and
> RPM is what matters?
>
> Ben Wagner
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